For example, in Japanese Patent No. 5,559,097, there is disclosed an exhaust system having two tail pipes which project from silencers in the rearward direction of a vehicle. A pressure control valve for control an exhaust pressure is arranged within a duct of one of the two tail pipes, and the pressure control valve is not arranged within a duct of the other tail pipe. This pressure control valve is formed of a valve of a normally closed type and is maintained in a valve closing state by spring force of a coil spring at the time of low load when the exhaust pressure of the exhaust gas is low.
In the case where the exhaust pressure of the exhaust gas becomes larger than the spring force of the coil spring at the time of high load when the exhaust pressure is high, the pressure control valve is configured to be switched from the valve closing state to a valve opening state.
BY the way, in the exhaust system disclosed in Japanese Patent No. 5,559,097, the exhaust gas is discharged only from the other tail tape in which the pressure control valve is not arranged, for example, at the time of the low load when the exhaust pressure is low. Therefore, in the case where the two tail pipes are arranged in parallel with each other so as to extend in the rearward direction of the vehicle, there is a possibility of deterioration in merchantability because of the unnaturalness when inspected from the outside as the exhaust gas is discharged only from one of the tail tapes.
Further, in some cases, there is a possibility that a person who inspects the two tail pipes from the outside may erroneously recognize that one of the tailpipes does not work properly because of clogging or the like.